#ifndef _PVCLOCK_GTOD_H
  #define _PVCLOCK_GTOD_H
  
  #include <linux/notifier.h>
  
  /*
   * The pvclock gtod notifier is called when the system time is updated
   * and is used to keep guest time synchronized with host time.
   *
   * The 'action' parameter in the notifier function is false (0), or
   * true (non-zero) if system time was stepped.
   */
  extern int pvclock_gtod_register_notifier(struct notifier_block *nb);
  extern int pvclock_gtod_unregister_notifier(struct notifier_block *nb);
  
  #endif /* _PVCLOCK_GTOD_H */